Chemical warfare (CW) agents and toxic industrial chemicals/materials (TIC/TIM) can pose a significant threat to military and civilian personnel and resources. Despite significant research, existing materials and methods for agent neutralization and mitigation are not effective for achieving rapid catalytic destruction of a wide range of chemical threat agents under mild conditions.
Chemical warfare nerve agents, blister agents, most other CW agents, and most significant TIC/TIM threat agents act through electrophilic reactions on nitrogen-containing nucleophilic residues on enzyme and protein molecules in exposed tissue and mucous membranes. The most highly toxic CW agents are drug-like, hydrophobic molecules having rapid transdermal/transmembrane transport and high reactivity in hydrophobic environments. Their hydrophobicity makes them difficult to transport into water and to hydrolyze by conventional aqueous pH-driven processes, which are typical routes to detoxification.
Existing broad spectrum technologies for threat mitigation generally rely on sorbent materials, combined with non-specific oxidation processes or pH-driven hydrolysis of agents by caustic. High temperature, high pressure hydrolysis with strong caustic is a widely used process for CW agent destruction in controlled reactor environments, such as those used for weapon demilitarization. However, the process is not effective for decontamination in ambient conditions or without damage to structures and surfaces. Caustic conditions are generally considered to be pH 10 or higher. By contrast, compatibility with skin, paint, fabric and other sensitive surfaces generally requires threat destruction that is effective nearer neutral pH, in the range of pH 5-10, and more preferably in the range of pH 6-9 or pH 7-8. Because most known mitigant materials are not catalytic, large quantities of mitigant are usually needed to handle even modest amounts of a threat agent. Solution peroxide carriers also have been disclosed, e.g., in Morrissey et al. U.S. Pat. No. 6,960,701. Oxidant vapor materials, vaporous hydrogen peroxide and chlorine dioxide generally require equipment for on-site generation of the mitigant materials, and difficulties with storage of precursor materials are often encountered. In general, these mitigant materials are costly, corrosive, difficult to handle, and may create significant damage to the structures to which they are applied. Recently, surface-bound chloramide oxidants have shown promise for biological threat destruction on fabrics and other surfaces. However, these approaches still lack the generality and capacity needed for chemical threat protection. More recently, enzymatic destruction has also been pursued, but these methods are generally costly and inefficient because of the complexity and large molar mass of typical enzymes, and in some cases chiral selection may enrich the more toxic enantiomer of a threat agent.